1. Field of the Invention
The present invention relates to a valve for a dust collector, which is capable of supplying a pressure fluid to a main dust collector body or which is capable of stopping the supply of the pressure fluid by opening/closing a fluid passage in accordance with a displacement action of a diaphragm.
2. Description of the Related Art
It has been hitherto known to collect the dust or the like such that a pressure fluid (air), which is supplied into a main dust collector body, is discharged from a plurality of nozzles to blow off the dust or the like trapped in the main dust collector body so that the dust or the like is allowed to fall. In this procedure, a valve for a dust collector is used, which functions to supply the pressure fluid into the main dust collector body or stop the supply of the pressure fluid.
As shown in FIG. 5, the valve for the dust collector concerning the conventional technique has a main valve body 3 which is formed with an inlet port 1 and an outlet port 2, and a diaphragm 6 which is flexibly bent in accordance with a differential pressure with respect to a diaphragm chamber 4 to open/close a passage 5 for making communication between the inlet port 1 and the outlet port 2. An unillustrated solenoid-operated valve is carried on an upper portion of the main valve body 3. An unillustrated valve plug is displaced in accordance with an exciting action of a solenoid of the solenoid-operated valve to discharge the pressure fluid in the diaphragm chamber 4 to the outside. Thus, the pressure in the diaphragm chamber 4 is adjusted.
The diaphragm 6 is held between an upper plate 7 having a large diameter and a lower plate 8 having a small diameter. The diaphragm 6 is in a state in which it is always urged downwardly by a resilient force of a spring member 9.
However, in the case of the valve for the dust collector concerning the conventional technique described above, when the diaphragm 6 is displaced upwardly to make communication between the inlet port 1 and the outlet port 2, a force is applied to tension the diaphragm 6 downwardly by the pressure fluid having a large volume supplied from the inlet port 1.
Therefore, the following inconvenience arises. That is, the tensioning force is directly applied to a portion A of the diaphragm 6 except for portions thereof which are held by the upper and lower plates 7, 8. If any excessive load, which is not less than the film thickness strength, is exerted on the portion A, the diaphragm 6 is damaged to cause any malfunction of the valve for the dust collector. Another inconvenience also arises such that the diaphragm 6 is fatigued by the use for a long period of time, and the durability of the valve for the dust collector is deteriorated.
A general object of the present invention is to provide a valve for a dust collector, which makes it possible to avoid any damage of a diaphragm for opening/closing a fluid passage and improve the durability, by mitigating the load on the diaphragm generated under the action of a flowing pressure fluid.
The above and other objects, features, and advantages of the present invention will become more apparent from the following description when taken in conjunction with the accompanying drawings in which a preferred embodiment of the present invention is shown by way of illustrative example.